Many features (like mobile apps) require active validation through Emby's official servers. If these servers cannot verify a legitimate key, the feature will remain locked regardless of local "patched" status.
You don't always need a Premiere key to enjoy the platform. Many core features are completely free: Free Features emby premiere lifetime key free patched
Stick with the free version of Emby! Many users find that the basic, free tier is more than enough for simple local network streaming. Many features (like mobile apps) require active validation